Project Summary The identification of cancer metastases to the bony vertebral column obligates the treating clinician to make a surgical decision. If the spine is deemed unstable and at risk for fracture, then the patient will undergo a major spinal operation, and will often spend much of their remaining life recuperating from it. Vertebral body metastasis is sometimes treated with corpectomy of the affected vertebral body and adjacent intervertebral discs, creating a non-contained skeletal defect needing anterior column spinal reconstruction and posterior instrumentation. Reconstructive techniques requiring both an anterior surgical exposure (reconstruction of affected vertebra) and a posterior exposure (instrumentation of the spine) are quite invasive for these patients, while a posterior-only surgical approach requires small implants for anterior spinal column reconstruction. Intervertebral expandable titanium cages, although effective for this reconstruction, are expensive, and can represent the dominant cost for the reconstructive spinal procedure. In addition, they are often too large to insert safely from the posterior surgical approach. Thus, a critical need exists to provide these frail patients with a lower surgical burden while at the same time improving their quality of life. This research proposal aims to address a critical issue involved in the care of patients with metastatic spine defects. The goals of this proposal are to develop a novel expandable biomaterial system that can be delivered via a posterior-only surgical approach, would provide rigidity and stability to the spine, and would be much more cost effective than current expandable metal cages